Maintaining thermal comfort in buildings is essential since it affects user's health and performance. Thermal comfort standards provide reference values for indoor environmental parameters; however, they cannot incorporate gender and age in their theories, in which the predicted mean vote (PMV) is used. The aim of this study was to investigate the effects of gender and age on thermal sensation, preference and acceptability as well as verifying the applicability of the PMV model. In order to obtain PMV and actual mean vote values, in situ measurements and surveys were carried out simultaneously in a religious building in Turkey. Statistical analyses, including the Shapiro-Wilk, Levene, Kruskal-Wallis and Games-Howell tests, were conducted to understand the statistical significance between females and males as well as four age groups. The results show that the PMV model is applicable for both females and males; however, it cannot be verified for all age groups except for the age group of 46-65 years. The relationship between thermal sensation and age group is stronger compared with that between thermal sensation and gender. Moreover, the effect of age group on thermal preference and thermal acceptability is statistically significant, whereas that of gender is not significant.